1. Field of the Invention
The present invention generally relates to a wireless mobile communication system, and more particularly, to a method of transmitting/receiving channel status information in which a User Equipment (UE) measures channel quality (wireless channel status) and informs an evolved Node B (eNB) of a measurement result in a wireless mobile communication system applying a multi-access scheme using a multi-carrier, such as an Orthogonal Frequency Division Multiple Access (OFDMA) scheme.
2. Description of the Related Art
A current mobile communication system has been developed to a high speed and high quality wireless packet data communication system to provide a data service and a multimedia service in addition to providing an initial service mainly based on a voice service. An evolved 3rd Generation mobile communication system standard employing a multiple access scheme using a multi-carrier is progressed by various standardization organizations, such as 3rd Generation Partnership Project (3GPP), 3GPP2, Institute of Electrical and Electronics Engineers (IEEE), and the like. Recently, various mobile communication standards including Long Term Evolution (LTE) of 3GPP, Ultra Mobile Broadband (UMB) of 3GPP2, 802.16m of IEEE and the like have been developed to support a high speed and high quality wireless packet data transmission service based on the multiple access scheme using the multi-carrier.
The evolved 3rd Generation mobile communication systems, such as LTE, UMB, 802.16m, and the like, are based on a multi-carrier multiple access scheme, apply beam-forming to improve a transmission efficiency, and use various technologies including an Adaptive Modulation and Coding (AMC) method, a channel sensitive scheduling method, and the like. The various technologies improve system capacity performance by improving the transmission efficiency through a method of concentrating transmission power transmitted from a plurality of antennas or controlling an amount of transmitted data according to channel quality and selectively transmitting data to a user having better channel quality. Since most of such schemes are performed based on channel status information between an evolved Node B (eNB) (or Base Station (BS)) and a User Equipment (UE) (or a Mobile Station (MS)), the eNB or the UE is required to measure a channel status between the eNB and the UE. A Channel Status Indication Reference Signal (CSI-RS) is used for measuring the channel status. The aforementioned eNB refers to a downlink transmission device and an uplink reception device located at a predetermined location, and one eNB performs transmission/reception for a plurality of cells. In one mobile communication system, a plurality of eNBs are geographically distributed and each of the eNBs performs transmission/reception of a plurality of cells.
Existing 3rd and 4th Generation mobile communication systems such as LTE/LTE-A use a Multi Input Multi Output (MIMO) technique of performing transmission by using a plurality of transmission/reception antennas in order to expand a data transmission rate and system capacity. The MIMO technique transmits a plurality of information streams spatially divided, by using a plurality of transmission/reception antennas. As described above, transmission of the plurality of information streams spatially divided is referred to as spatial multiplexing. In general, a number of information streams to which the spatial multiplexing can be applied varies depending on a number of antennas of a transmitter and a receiver. Information on the number of information streams to which the spatial multiplexing can be applied is generally referred to as a rank of corresponding transmission. The MIMO technique supported by the LTE/LTE-A Release 11 standard supports spatial multiplexing in a case where each of transmission and reception antennas is 8 and maximally supports rank 8.
However, when a plurality of transmission/reception antennas exist, large resources are consumed in measuring and reporting channel statuses between antennas of the transmitter and the receiver, so that a solution to the above problem is required.